Although applicants' scale may be utilized in many situations when portability and hand useage are required the advent of tournament and other fishing contests has resulted in a demand for an accurate and also readable and, on occasion a photographable scale. Spring loaded scales, strain gauge scales and other similar load cell scales have proved to be ineffective and expensive. The applicants' device provides a relatively inexpensive unit which measures the capacitance between two plates of known area and known beginning spacing and utilizing the dielectric constant of air to determine the initial capacitance at unweighted levels and the increase in capacitance upon loading thereof.
In their search of the prior art the applicants have found several United States Patents pertaining to capacitive loading and weighing situations. These include the Patents to Harrington, et al, No. 4,629,019; Jeffrey, No. 4,520,885; Inoue, No. 4,586,576; Harrington, et al, No. 4,585,082; and Bovee, No. 4,679,643.
First, it appears that none of these scales are applicable in any manner to hand held or portable useage. Further, none of these patents provide a simple sandwich structure incorporating a stationary and a moveable beam, moveable in response to weight placed on the moveable beam for the changing of capacitance of the air gap between itself and the stationary plate and none of these patents consider the concept of digital readout arrangements.
It is therefore an object of the applicants' invention to provide a hand held, portable scale for weighing a range of articles which includes a capacitance measuring structure incorporating a stationary plate and a weightable, moveable plate with provided circuitry to measure the capacitance increase upon movement of the moveable plate with means of converting this capacitance change to a digital readout.
It is still a further object of the applicants' invention to provide a portable, hand held scale particularly oriented to the weighing of relatively small objects, possibly under one hundred pounds wherein a stationary plate is provided and a second plate having a moveable portion is provided in spaced relation to the stationary plate with means for attaching a weight to the moveable section of the plate whereby the capacitance controlled by the distance between the stationary and moveable plate is modified in accordance with the weight and circuitry means are provided to measure the increase in capacitance due to the weight and conversion means are provided to provide the user a digital readout of the capacitance change through actual weight readout.
It is a further object of the applicants' invention to provide a portable, hand held scale which operates on a capacitance change which capacitance change is a result of a weight placed on a hook which extends through the case of the unit and is physically attached to a moveable capacitance plate.